Duo-block safety device

ABSTRACT

A safety stop for a traveling block of a drilling rig utilizes a cam carried by and rotating in unison with a shaft which in turn is driven in geared relationship by the rotating shaft of the power winding drum of the traveling block. A cam follower actuated valve initiates means to stop the travel of the block at the upper and lower limits. By disengaging a floating clutch, an operator can rotate the cam relative to its carrying shaft to quickly and easily adjust the upper and lower stop limits of the traveling block.

finite States atent H 1 mick [451 Aug. 15, 1972 DUO-BLOCK SAFETY DEVICEPrimary Examiner-Even C. Blunk 72 Inventor: Theodore B. Houck, 3636 s.Aswan Cherry Florence Place, Tulsa, Okla. 74105 Anomey Head & Johnson[22] Filed: Aug. 5, 1970 57 CT [21] Appl.No.: 61,142

A safety stop for a traveling block of a drilling rig utilizes a camcarried by and rotating in unison with a 52 us. an ..254/173 R, 192/703,192/139 shaft which in turn is driven in geared relationship y 51 Int.Cl. ..'..B66d 1/48 the rotating shaft of the Power winding drum of the[58] Field of Search ..254/145, 146, 168, 187, 173; traveling block. Acam follower actuated valve inl92/70.23, 70.24, 703, 93, 138, 139itiates means to stop the travel of the block at the upper and lowerlimits. [56] References Cited By disengaging a floating clutch, anoperator can UNITED STATES PATENTS rotate the cam relative to itscarrying shaft to quickly d '1 d tth d1 t 1' 't fth 3,101,828 8/1963Wilson ..192/139 an e275 a jug e pperan 6 traveling block. 2,899,0388/1959 Wellauer ..192/68 2 Claims, 6 Drawing Figures 92 54 4a fie 7 56ii 72 52 i 70 58 1 9 "\Mwm- IV.

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THEODORE a. HOUCK ATTORNEYS DUO-BLOCK SAFETY DEVICE CROSS REFERENCE Thisapplication is not related to any known US. or foreign patentapplication.

BACKGROUND OF THE INVENTION This apparatus pertains to safety devicesand more particularly to a safety stop device for a traveling blockdrilling rig. Safety traveling block stops have heretofore been knownfor limiting the upward and/or downward movement of a traveling block.One type of such traveling block stop device which controls both themaximum upward and downward movement of the traveling block utilizes acam to control the actuation of valve means which in turn controls theinverse actuation of a power winding drum clutch and brake to stoptravel of the block. The cam is fixedly carried on shaft which is drivenin geared relationship to the shaft on which the power winding drum ismounted; the gearing being such that the driven shaft rotates less than360 during maximum travel of the block.

A disadvantage presented by this type of clutch oriented stop mechanismis the fact that since the cam is rigidly secured to the output shaft ofthe gear reduction unit, the upper and lower stop limits can be adjustedonly by using hand tools to detach the cam from the shaft, rotating thecam relative to the shaft and then rigidly reattaching the cam to theshaft for common rotation therewith. This procedure is tedious andtimeconsuming.

It is therefore an object of this invention to present a cam operatedsafety stop device for a traveling block having means thereon forquickly and easily adjusting the upper and lower stop limits of theblock.

It is another object of this invention to present a cam operated safetystop device wherein the engagement and disengagement of the cam with theoutput shaft of the gear reduction unit is controlled by clutch means.

A still further object of this invention is to present a rotates inunison with the output shaft of the gear cam operated safety stop devicefor the traveling block SUMMARY OF THE INVENTION Generally the inventionpresents a cam operated safety stop device for a traveling block of adrilling rig wherein the cam is carried on the output shaft of a gearreduction unit which in turn is interconnected to and driven in gearedrelationship with the shaft on which the power winding drum of thetraveling block is mounted. A clutch controls engagement anddisengagement of the cam with the output shaft of the gear reductionunit. In the disengaged position, the cam is free to rotate relative tothe shaft such that the position of the upper and lower stop limits ofthe traveling block can be adjusted. In the engaged position, the camstop limit circuitry which in turn stops the rotation of the powerwinding drum.

DETAILED DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a drillingderrick having installed thereon a traveling block system and showingthe safety stop device interconnected to the power winding drum shaftthereof.

FIG. 2 is a top view of the safety stop device of this invention.

FIG. 3 is a side view of the safety stop device of this invention.

FIG. 4 is a cross-sectional side view of the safety stop device of thisinvention.

FIG. 5 shows schematically a typical circuit utilizing the safety stopdevice of this invention.

FIG. 6 is a partial side view of the safety stop device showing the camdisc and cam follower actuated valve thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Looking now at FIG. 1of the drawings, the numeral 10 designates a drilling rig derrick havinginstalled thereon a drilling rig hoist mechanism or draw works generallydenoted as 12. A swivel 14 is suspended from a traveling block 16 whichin turn is suspended on a cable 18. The cable passes off of a drum 20and over crown block sheaves 22 which support the traveling block 16 forupward and/or downward movement within derrick 10 as is well understoodin the art.

The traveling block safety stop device which is designated generally as24 is attached through a chain and sprocket arrangement 26 or othersuitable means to the power winding drum shaft 28 which shaft rotatablycarries the power winding drum 20.

Turning now to FIGS. 2 and 3 of the drawings, the safety stop device canbe housed in an enclosure 30 if desired. Chain and sprocket 26 driven bythe drum shaft 28 feeds the drive shaft of a gear reduction unit 32which has a bidirectional output shaft 34. Gear reduction unit 32 has alow speed gear ratio such that the rotation of output shaft 34 is lessthan 360 for the maximum desired travel of the traveling block 16.

Referring now to FIG. 4, coaxially received on output shaft 34 and keyedthereto by means of key 36 is a tubular hub 38. The subsequentdiscussion of the components of the block safety device will bedescribed in reference to hub 38; nevertheless it is to be understoodthat if desired output shaft 34 can directly receive these componentsdiscussed thereby eliminating the need for hub 38. However, by the useof hub 38 a standard commercially available gear reduction unit can bepurchased and used without modification. The rearward portion of hub 38is bounded by a perpendicular lip 40 around the periphery thereof andthe forward portion is reduced diameter and contains male threads 42.

Equidistantly spaced around the periphery of hub 38 are a plurality oflongitudinal grooves 44 which progress the length of the hub and whichreceive the tongues of spaced apart annular clutch plates 46A and 46Bcoaxially sleeved over hub 38. Clutch plate 46 abuts against lip 40.

As can be appreciated Clutching plates 46A and 468 so received on hub 38are affixed to the hub for common rotation therewith but are capable oflongitudinal movement relative to each other and to hub 38 between afirst engaged position and a second disengaged position.

Affixed to the confronting sides of clutch plates 46A and 46B areannular friction materials 48 which are adapted in the engaged positionof the clutching plates to fixedly engage a cam disc 50 having a camportion 51 sleeved over hub 38 and sandwiched between clutching plate46A and 46B. Cam disc 50 in the disengaged position of the clutchingplates is rotatable rela tive to hub 38 and output shaft 34 and in theengaged position is fixedly interconnected to hub 38 for rotation inunison with hub 38 and output shaft 34.

Longitudinal movement of the clutching plates 46A and 468 relative toeach other is controlled by a plurality of dogs 52 which in turn arecontrolled by a manually operable ring clutch 54.

Each dog has a flared rearward end bearing against the outer surface offorward clutching plate 46A and includes a plurality of rollers 58 whichenable the dog to rock inwardly and outwardly. Ring clutch 54surrounding the dogs 52 and retaining them within grooves 44 is adaptedon being manually pushed rearwardly to force the flared end 56 of dogs52 inwardly about the intermediate roller which in turn forces theclutching plates into frictional engagement with cam disc 50 therebyinterlocking the hub for common rotation. On reverse movement of ringclutch 54 that is on being drawn forwardly ring clutch 54 bears againsta projection 60 on the forward end of the dogs to cause flared ends 56to rock outwardly to disengage the clutch plates from cam disc 50thereby rotatably disconnecting the cam disc from the hub and enablingthe cam disc to be rotated relative to the hub and output shaft.

Ring clutch 54 may be constructed as a continuous circular piece or maybe comprised of two semi-circular components 62A and 62B securedtogether as by bolts 64 as shown in FIG. 3. A zerk fitting 66 forreceiving grease or other lubricant facilitates the operation of thering clutch. The frictional tension with which clutching plates 46A and46B engage cam disc 50 is adjustably determined by an annular tensioningnut 68 which is threadably received on threads 42 on the reduceddiameter end of hub 38 and which has an arcuate surface abutting theforward rollers 58 of dogs 52. Clockwise rotation of tensioning nut 68longitudinally slides the dogs 52 forwardly to increase the frictionaltension engagement of the clutching plates with cam 50.Counter-clockwise rotation reduces such tension. The inner surface oftension ring 68 includes a slot having received therein a metallic bar70 which is transversely movable by means of a set screw 72. Once theproper tension has been determined the metallic bar is moved inwardly tobear against threads 42 on the hub thereby locking the tensioning nut 68in a fixed position.

Bindingly engaging the peripheral edge of cam disc 46 and responsive tothe angular position thereof is a spring-loaded cam follower actuatorarm 74 of a pilot switch 76. Cam follower actuator arm 74 functions inthe same manner as standard cam follower actuators known in the art in;that as cam disc 50 rotates in unison with the output shaft 34, theactuator is responsive to the profile of cam disc 50 and, as it ridesonto the cam portion, is depressed to activate pilot switch 76.

Pilot switch 76 is interconnected to and initiates circuitry to stoptravel of the block 16 as it reaches either the predetermined upper orlower stop limits. Pilot switch 76 and associated circuitry employcommercially available components and may be either electrical,hydraulic, or pneumatic. For example pilot switch 76 may be connected toan air reservoir through filters 78 through conduit 80 and the outletthereof may be connected in parallel to the control ports ofa brakeactuator cylinder 82, valve, a high clutch air line valve 84, a lowclutch air line valve 86 and a throttle control air line valve 88 as isshown in FIG. 3 in a manner known in the art; a typical schematic ofwhich is shown in FIG. 5. A reset valve may be inserted in the circuitryas shown in FIG. 5. Upon depression of the actuator of the reset valve,the block safety device is bypassed thereby enabling the traveling blockto be moved beyond the stop limits. The circuitry for use of electricalor pneumatic components is similar to the previously discussed circuitfor air components and is known to one skilled in the art.

In operation, ring clutch 54 is drawn forwardly to disengage clutchingplates 46A and 46B from cam disc 50, and the cam disc is then rotatedrelative to hub 34 until the profile of the cam disc 50 is in a positionrelative to the cam actuator arm 74 which effect the desired upper andlower stop limits of the traveling block 16. Clutching plates 46A and46B are then forced into en gagement with the cam disc 50 in the manneras previously discussed to interlock cam disc 50 with shaft 34 andtubular hub 38 for common rotation therewith. The device is now readyfor operation. During operation, the traveling block 16 is raised andlowered by rotation of power winding drum 20 mounted on shaft 28 in theusual manner.

Output shaft 34 rotates in geared relationship to the rotation of shaft28. When the traveling block 16 reaches the desired upper or lower stoplimit, cam actuator arm 74 will ride up onto cam portion 51 of cam disc50 and be depressed to actuate pilot switch 76 which in turnsimultaneously actuates the brake actuator cylinder 82 and clutch valves84 and/or 86 and the air throttle device 88 to stop the rotation of thepower winding drum 20, by disconnecting the hoist drum clutches dumpingthe engine throttle and setting the drum brake.

Upon reversing the rotation of the power winding drum, the cam followeractuator arm 74 will overrun cam portion 51 and return to its normalposition. Operation of the traveling block then continues in the normalmanner until cam follower actuator arm 74 is again depressed.

Wen it is desired to change the upper and lower stop limits, clutchingplates 46A and 46B are disengaged from cam disc 50, the disc rotatedrelative to shaft 34 and hub 38 to a position which effects the desirednew upper and lower limits and the clutching plates 46A and 46B areagain engaged to frictionally interconnect cam disc 50 to the shaft fora rotation therewith.

The safety device as discussed heretofore while enabling the upper andlower stop limits to be adjustably varied, does not have the capabilityof adjusting the length of travel of block 16 between the upper andlower stop points since the profile of cam disc 54 is not changed.

Referring back to FIG. 4, this capability of adjusting the length oftravel of block 16 between the upper and lower stop points is attainedby a cam ring 92 slidably received in a groove 93 cut in the outerperipheral edge of the cam portion 51 of cam disc 50. Ring 92 soreceived on cam disc 50 has the peripheral edge thereof coincidentalwith the edge of cam portion 51 and is in alignment with cam followeractuator 74.

Looking now at FIG. 6, set screws 94 hold the ring in a fixed position.When it is desired to change the profile of the cam disc 50 in order tochange the travel length of safety block 16, all that is necessary to dois to loosen set screws 94 and manually slide the cam ring 92 relativeto the component 51 until the desired new cam profile is attained whicheffects the desired length of travel between the stop limit points.

During the detailed description of the preferred embodiment specificlanguage has been used for the sake of clarity; however it is to beunderstood that the language used are not words of limitation andinclude all equivalents which operate in a similar manner. As it will beappreciated, the safety bock of this device possesses means for easilyadjusting both the upper and lower stop limits of a traveling block andalso the length of travel between the stop points.

What is claimed:

1. In a hoist system having a traveling block suspended on a cabledriven by a power winding drum mounted on a bidirectional rotatabledrive shaft, said drum having a clutch mounted on said shaft of saidwinding drum and a brake in braking relationship therewith, said brakeand said clutch being simultaneously inversely actuated by valve meanshaving a cam follower actuator, a safety apparatus for stopping at upperand lower limits the travel of said block, comprising:

a gear reduction unit interconnected in driving relationship with saiddrive shaft having an output shaft rotating less than 360 in response totravel of said block between said upper and lower limits;

a cam disc having a cam profile on the circumferential periphery thereofengaging said cam follower actuator of said valve means, said camfollower actuator being responsive to the rotative movement of the saidcam disc;

a pair of spaced-apart clutch plates coaxially mounted on said outputshaft and rotatable in unison therewith, said cam disc being sandwichedbetween said clutch plates and rotatable by hand about said outputshaft, said clutch plates being longitudinally movable relative to eachother between engaged and disengaged positions; and

means for longitudinally moving said clutch plates between said engagedand disengaged positions whereby in said engaged position said cam discis fixedly engaged by said clutch plates to interconnect said cam discto said output shaft for common rotation therewith and in saiddisengaged position said cam disc is rotatable by hand relative to saidoutput shaft for adjusting the limits of travel of said block. 2. Anapparatus as in claim 1 wherein said cam in-

1. In a hoist system having a traveling block suspended on a cabledriven by a power winding drum mounted on a bidirectional rotatabledrive shaft, said drum having a clutch mounted on said shaft of saidwinding drum and a brake in braking relationship therewith, said brakeand said clutch being simultaneously inversely actuated by valve meanshaving a cam follower actuator, a safety apparatus for stopping at upperand lower limits the travel of said block, comprising: a gear reductionunit interconnected in driving relationship with said drive shaft havingan output shaft rotating less than 360* in response to travel of saidblock between said upper and lower limits; a cam disc having a camprofile on the circumferential periphery thereof engaging said camfollower actuator of said valve means, said cam follower actuator beingresponsive to the rotative movement of the said cam disc; a pair ofspaced-apart clutch plates coaxially mounted on said output shaft androtatable in unison therewith, said cam disc being sandwiched betweensaid clutch plates and rotatable by hand about said output shaft, saidclutch plates being longitudinally movable relative to each otherbetween engaged and disengaged positions; and means for longitudinallymoving said clutch plates between said engaged and disengaged positionswhereby in said engaged position said cam disc is fixedly engaged bysaid clutch plates to interconnect said cam disc to said output shaftfor common rotation therewith and in said disengaged position said camdisc is rotatable by hand relative to said output shaft for adjustingthe limits of travel of said block.
 2. An apparatus as in claim 1wherein said cam includes means for adjusting the profile of said camdisc to adjust the length of travel of said block between said stoplimits.